CN104502980B - A kind of discrimination method of electromagnetic Earth impulse response - Google Patents
A kind of discrimination method of electromagnetic Earth impulse response Download PDFInfo
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Abstract
The invention discloses a kind of discrimination method of electromagnetic Earth impulse response, electromagnetic Earth impulse response identification system is designed according to Wiener Hopf equations, artificial source's electromagnetic method transmitted waveform is encoded and launched using pseudo-random sequence, collection is synchronized with response observation signal to coded excitation waveform in observation, the method based on cross-correlation identification principle is used afterwards, the complex effects of transmission signal autocorrelation sidelobe are eliminated in receiving and transmitting signal, realizes and the high accuracy of the earth impulse response is recognized.Compared with traditional step source forcing mode, method of the invention removes the influence of transmitted waveform autocorrelation sidelobe in transmitting-receiving cross-correlation, so as to significantly improve the identification precision of electromagnetic Earth impulse response.
Description
Technical field
The present invention relates to field of geophysical exploration, more particularly, to a kind of identification side of electromagnetic Earth impulse response
Method, this method accurately picks out the earth impulse response suitable for the observation data by geophysics electromagnetism exploration system,
Be particularly suitable for use in the geophysics electromagnetism exploration system based on coded excitation electric current.
Background technology
Develop with scientific and technical, the object that researcher faces is complicated all the more, such as chemistry and chemical engineering process, biological doctor
System, social economic system, environmental system etc., these complicated objects are generally difficult to obtain its number by the method for theory analysis
Learn model.Research to this class object just proposes a problem：How the mathematical modeling of this class object is distinguished with parameter
Know
It is based on above-mentioned current demand and generates system identification theory and method.System Discrimination is Comtemporary Control Theory
One branch, it constitutes three big pillars of Comtemporary Control Theory with state estimation, control theory.Go out from the angle of control theory
Hair, the popular definition of System Discrimination is according to controlled device or is identified the input of system, exports observation information to estimate its
Mathematical modeling.Every needs are observed by the input and output to system, using observe data to the mathematical modeling of system with
The occasion that important parameter is studied belongs to System Discrimination process.
Electromagnetic method relies on outside sources (including artificial source and natural source) to the earth as one kind of geophysical exploration method
Medium enters row energization, and the earth is set up in the response (traditionally referred to as secondary field) that is produced after being activated by observing the earth medium
Medium electrical parameter with changes in spatial distribution model.This process is actually one from the point of view of Comtemporary Control Theory
The process of system identification, it includes 4 aspects：Driving source, signal observation, the foundation of identification model and system identifying method.
For common frequency domain method, its driving source includes natural source and artificial source, and (common current waveform is dutycycle
Bipolar square wave for 100%)；Signal, which is observed, includes the collection for observing data and the processing of observation data, observes adopting for data
Collection generally comprise omnidirectional distribution electric field observation and magnetic field observation, observation data processing generally comprise filtering etc. it is pretreated
Journey；The foundation of identification model is according to far field it is assumed that making emission source meet plane wave condition in measuring point, afterwards according to surge impedance model
Set up mapping relations；System identifying method refers generally to the refutation process based on least square method.
For common time-domain method, its driving source is generally artificial source, and (common current waveform is dutycycle non-100%
Bipolar square wave, bipolarity semisinusoidal and dutycycle for 100% bipolarity trapezoidal wave, bipolarity triangular wave)；Signal is seen
Surveying includes the collection for observing data and the processing of observation data, and the collection of observation data generally comprises simple component or multi -components magnetic field
Observation and/or the observation of simple component or multi -components electric field, the processing of observation data generally comprise smooth grade for preprocessing process；Recognize mould
The foundation of type is generally divided into far field method and near region method, by specifically receive and dispatch and observation condition set up relative simplicity mapping close
System；System identifying method generally comprises the refutation process based on least square method and the imaging process based on simplified algorithm.
Either frequency domain method or time-domain method, can actually be divided into two for whole identification process
Individual link：First link realizes the identification to electromagnetic Earth impulse response, and second link is realized is rung by electromagnetic Earth impulse
Tackle the identification of underground medium electrical parameter distributed model.First identification link fully belongs to "black box" identification, because it is only
It can be recognized by the response data of test system；Second identification link belongs to " ash bin " identification, because electromagnetic Earth system
Mapping basic law between system response and the distribution of underground medium electrical parameter is to grasp and (be based on maxwell equation group), but
Some specific mechanism are not yet clear, therefore can be referred to as " ash bin " identification.Because the input signal of second identification link is
The result of first identification link, therefore the identification precision of second link will largely depend on distinguishing for first link
Know precision.So, the identification precision for how improving first link is just significant for the precision entirely recognized.
The identification process of electromagnetic method does not have real-time typically, according to System Discrimination term, belongs to off-line identification.Distinguish offline
Know and there are certain requirements for input signal tool, its minimum requirements is that in whole observation cycle, all mode of system must quilt
Input signal Persistent Excitation.Here it is the bandwidth of identification system, input signal band will can be covered by requiring the bandwidth of input signal
Wide sufficiently large relative to identification system bandwidth, then the identification to identification system also will be more accurate.Therefore, in order to more high-precision
Realize System Discrimination degree, input signal must be just designed, it includes the type selecting, amplitude and bandwidth of input signal
Etc. the selection of parameter.Common artificial source's electromagnetic method excitation waveform from this angle, it has in terms of bandwidth, amplitude
Shortcoming part.Exactly because in this way, increasing researcher considers to enter using with the pseudorandom two with the most long circulating cycle
Sequence processed is used as excitation sources waveform for the coding waveforms of representative.
Pseudo-random binary sequence (Pseudo Random Binary Sequence, abbreviation PRBS) is entered to a variety of two
The general name of pseudo-random sequence processed, so-called binary system means that each random quantity in sequence only has 1 and 0 two logic state.
In all PRBS, there is a class to be referred to as linear shift register sequence (the Maximal Length with the most long circulating cycle
Sequence, abbreviation m-sequence), be also easy to realize because of the property with approximate white noise, in engineering, be widely used as be
The input signal of system identification.
Coding waveforms are used in artificial source's electromagnetic survey as emission current waveform not fangle.Early in 20 generation
Discipline the seventies, Quincy, Davenport, Lindsay and Duncan have just expanded the people based on code current waveform
The research of work source electromagnetic prospecting system and method.At home, what is proposed after being good at nineteen eighty-twoSequence pseudo-random signal electricity
Method, and at the beginning of 21 century system has been carried out further perfect.1985 to 1986, China University of Geosciences's electrical method scientific research group existed
Under the hosting of Luo Yanzhong professors, carry out the development work of pseudo-random signal broadband induced polarization instrument.Last century the nineties, Strack exists
Similarly studied in its works using pseudorandomcode as LOTEM method transmitted waveforms, this research inspires Scotland
The researcher of Edinburgh University was proposed MTEM systems in 2004 or so.In ten years in past, the country is based on volume
The exploration system research of code emission current is also in the ascendant, and such as Zhao is green as team have developed suitable for ore deposit in 2007 to 2009
Produce the pseudo-random signal resistivity method reconnoitred and induced polarization method instrument KGR.The national great Scientific research equipment started for 2013 develops item
Mesh " research and development of deep resource detecting core equipment ", the expansion of its sub-project " multiple-passage large power electrical prospecting instrument " is compiled based on m-sequence
The electric-method exploration device research and development of code current waveform.
The general principle for carrying out System Discrimination using m-sequence is based on Wiener-Hopf equations.For as shown in Figure 2 one
Individual linear time invariant system：
Y (t)=z (t)+n (t) (13)
Z (t)=g (t) * u (t) (14)
Wherein u (t) is input signal, and g (t) is the impulse response of system, and z (t) is output signals of the u (t) Jing Guo system,
N (t) is noise, and y (t) is the output signal for including noise.System describe based on Fig. 2, only considers u (t) and z (t) first,
Wiener-Hopf equations can be written as：
CR (z, u)=g*AR (u) (15)
Wherein, CR (l, m) represents signal l and m cross-correlation, and AR (l) represents signal l auto-correlation.Formula (15) represents defeated
The convolution that the auto-correlation and system impulse for entering signal are responded is the cross-correlation of input signal and output signal.Consider noise n, then
Have：
CR (y, u)=CR (z, u)+CR (n, u)=g*AR (u)+CR (n, u) (16)
Formula (16) is the mathematical description of basic Correlation Identification method.Input signal is selected based on formula (16), it will
Ask including：First, input signal should have randomness, and the CR (n, u) in formula can be neglected；Secondly, input signal auto-correlation should
Form with similar δ (t) function, then can make g*AR (u) be approximately equal to g (t).
M-sequence can preferably meet above-mentioned requirements, therefore as a kind of common System Discrimination input signal.However,
Only above there is the characteristic of nonzero value on one point relative to δ (t) functions, even if m-sequence selects higher coding exponent number, shorter code
First width, the non-zero secondary lobe of its autocorrelation sequence spike both sides is still present.The influence of these secondary lobes is complicated and can not ignore, because
This EM method being had higher requirements for identification precision, then can not simply quote formula (16) and carry out the earth impulse response identification.
In summary, the identification carried out using m-sequence as excitation sources waveform to electromagnetic Earth impulse response, be with one
Row advantage, such as high noise immunity, broader bandwidth etc..However, being as excitation sources waveform based on m-sequence for using
System, because the method for how overcoming transmission signal autocorrelation sidelobe to influence is still immature, causes identification precision not enough.The present invention is just
It is to be directed to this problem, a kind of method for removing autocorrelation sidelobe influence is proposed, so as to significantly improve to the earth impulse response
Identification precision.
The content of the invention
In view of this, the invention discloses a kind of accurate discrimination method of electromagnetic Earth impulse response, with from transmitting-receiving result
In more accurately pick out mt impulse response,
To achieve these goals, as one aspect of the present invention, the invention provides a kind of electromagnetic Earth impulse sound
The discrimination method answered, it is characterised in that design electromagnetic Earth impulse response identification system according to Wiener-Hopf equations, is utilized
Pseudo-random sequence is encoded and launched to artificial source's electromagnetic method transmitted waveform, to coded excitation waveform and response in observation
Observation signal synchronizes collection, afterwards using the method based on cross-correlation identification principle, and transmitting letter is eliminated in receiving and transmitting signal
The complex effects of number autocorrelation sidelobe, realize and the high accuracy of the earth impulse response are recognized.
As another aspect of the present invention, present invention also offers a kind of discrimination method of electromagnetic Earth impulse response,
Comprise the following steps：
Artificial source's electromagnetic method transmitted waveform is encoded；
According to the coding generation transmitting drive signal；
Launched with the transmitting drive signal driving emitter；
Filled using being recorded known to system response function relation between the tape deck or each device responded with identical systems
Put and record storage is carried out to the emitter actual transmission current waveform and the response signal observed simultaneously；
The emitter actual transmission current waveform is calculated according to the emitter actual transmission current waveform of record
Auto-correlation function；
The response signal and the emitter observed described in the response signal calculating observed according to record is real
The cross-correlation function of border emission current waveform；
Based on cross-correlation identification principle, the complex effects of transmission signal autocorrelation sidelobe are eliminated by mathematical method, are realized
High accuracy identification to the earth impulse response.
Wherein, described is according to Wiener-Hopf equations the step of encoded to artificial source's electromagnetic method transmitted waveform
Encoded.
Wherein, described is to use pseudo-random binary sequence the step of encoded to artificial source's electromagnetic method transmitted waveform
Row, i.e., m-sequence is encoded.
Wherein, the step of auto-correlation function of the calculating emitter actual transmission current waveform includes：
Calculate AR (Tx(t)), wherein Tx(t) it is actual transmission current waveform, AR (l) expression signals l auto-correlation.
Wherein, the response signal that the calculating observation is arrived and the step of the cross-correlation function of emitter actual transmission current waveform
Suddenly include：
To RxAnd T (t)x(t) cross-correlation calculation is done：
CR(Rx(t), Tx(t))=CR (g (t) * Iw(t)*hr(t), Tx(t))+CR (v, Tx(t)) (3)
Wherein, actual transmission current waveform is Tx(t) response signal, observed is Rx(t) and electromagnetic Earth impulse ring
It should be g (t), Iw(t) it is the emission current waveform of emitter reality output, htr(t) it is for recording Iw(t) receiver is
System response, hr(t) it is the system response of the receiver for response signal observation, v is noise, and CR (l, m) represents signal l and m
Cross-correlation.
Wherein, the tape deck responded with identical systems or the known record of each apparatus system receptance function relation
Device meets following relation：
htr(t)=hr(t) (5)
Or htrAnd h (t)r(t) following relation is met：
htr(t)=f (t) * hr(t) (6)
Wherein, f (t) is known htrAnd h (t)r(t) relation function.
Wherein, the method based on cross-correlation identification principle, eliminates the complex effects of transmission signal autocorrelation sidelobe
Step includes：
And work as htrAnd h (t)r(t) when relation is as described above,
Then formula (4) can be turned to by matrix：
A=BG+cv (11)
Wherein：
NgTo recognize the sampling number of the earth impulse response；n1And n2Respectively a (n) samples with maximum in b (n) sequences
The sequence number of point；
Calculated by least square method, vector G is separated from vector A：
G=(BTB)-1BTA (12),
Thus obtained G is realized removes the influence of transmission signal autocorrelation sidelobe from transmitting-receiving cross-correlation, realizes
High accuracy identification to the earth impulse response.
Wherein, in the method based on cross-correlation identification principle, the complex effects of transmission signal autocorrelation sidelobe are eliminated
The step of in, to the formula (12) carry out successive ignition calculating, further to improve identification precision.
Wherein, cross-correlation identification principle is based on described, the step of eliminating the complex effects of transmission signal autocorrelation sidelobe
Also include carrying out debiasing processing to data before, i.e., signal bandwidth is limited in the step in corresponding scope using LPF
Suddenly；And
G amplitude is modified after identification is completed, in addition to according to receiver sample frequency, and G curves are entered
The step of row smoothing processing.
Understood based on above-mentioned technical proposal, the advantage for the method that the present invention is provided is：Propose the removal of complete set
The method of autocorrelation sidelobe effect, can carry out the identification of higher precision to electromagnetic Earth impulse response.From shown in Fig. 5 and Fig. 6
As a result understand, can significantly be lifted pair relative to original method (corresponding (16)) using the discrimination method that provides of the present invention
The identification precision of the earth impulse response.
Brief description of the drawings
Fig. 1 is the basic procedure block diagram of the electromagnetic Earth weighting function identification method of the present invention；
Fig. 2 is the schematic diagram of general linear system；
Fig. 3 is the autocorrelogram of m-sequence pseudorandomcode；
Fig. 4 is identification sampling process timing schematic diagram；
Fig. 5 is original method and the method for the invention provided to the identification result figure of theoretical the earth impulse response, wherein Fig. 5
(a) it is former methodical identification result, Fig. 5 (b) is the identification result of the inventive method；
Fig. 6 is original method and the method for the invention provided to the Identification Errors figure of theoretical the earth impulse response, wherein Fig. 6
(a) it is former methodical Identification Errors, Fig. 6 (b) is the Identification Errors of the inventive method；
Fig. 7 is actual transmission current waveform detail view；
Fig. 8 is actual observation signal detail figure；
Fig. 9 is the cross-correlogram of receiving and transmitting signal；
Figure 10 is the identification result curve map of the earth impulse response of the present invention.
Embodiment
For the object, technical solutions and advantages of the present invention are more clearly understood, below in conjunction with specific embodiment, and reference
Accompanying drawing, the present invention is described in further detail.
The present invention provides a kind of discrimination method of electromagnetic Earth impulse response, in being explored for geophysics electromagnetic method,
Its general principle is：Electromagnetic Earth impulse response identification system is designed according to Wiener-Hopf equations, pseudo-random sequence pair is utilized
Artificial source's electromagnetic method transmitted waveform is encoded, and coded excitation waveform is synchronized with response observation signal in observation and adopted
Collection, afterwards using the method based on cross-correlation identification principle, eliminates the complexity of transmission signal autocorrelation sidelobe in receiving and transmitting signal
Influence, realizes and the high accuracy of the earth impulse response is recognized.
The present invention is further illustrated with reference to Fig. 1.
As shown in figure 1, the discrimination method of the electromagnetic Earth impulse response of the present invention, specifically includes following steps：
Step 1：Artificial source's electromagnetic method transmitted waveform is encoded
The step of being encoded to artificial source's electromagnetic method transmitted waveform is encoded according to Wiener-Hopf equations
, wherein can be encoded using pseudo-random binary sequence, i.e. m-sequence.
Step 2：According to the coding generation transmitting drive signal
Step 3：Launched with the transmitting drive signal driving emitter
According to the discrimination method of the electromagnetic Earth impulse response of the present invention, based on cross-correlation identification principle, it is required to distinguishing
The receiving and transmitting signal of knowledge system is observed.Assuming that actual transmission current waveform is Tx(t) response signal, observed is Rx(t) with
And electromagnetic Earth impulse response is g (t), then there is following relation between three：
Rx(t)=g (t) * Iw(t)*hr(t)+v (1)
Tx(t)=Iw(t)*htr(t) (2)
Wherein Iw(t) it is the emission current waveform of emitter reality output, htr(t) it is for recording Iw(t) receiver
System response, hr(t) it is the system response of the receiver for response signal observation, v is noise.
Step 4：Using known to system response function relation between the tape deck or each device responded with identical systems
Tape deck carries out record storage to the emitter actual transmission current waveform and the response signal observed simultaneously
The discrimination method of the electromagnetic Earth impulse response of the present invention, uses the tape deck responded with identical systems or each
Tape deck known to system response function relation is simultaneously to actual transmission current waveform and the response signal observed between device
Carry out record storage, that is, require for record actual transmission current waveform with carry out response signal observation tape deck meet with
Lower relation：
htr(h)=hr(t) (5)
Or by actual observation, obtain relation function f (t), make htrAnd h (t)r(t) following relation is met：
htr(t)=f (t) * hr(t) (6)
Step 5：The emitter actual transmission electric current is calculated according to the emitter actual transmission current waveform of record
The auto-correlation function of waveform
Calculate AR (Tx(t)), wherein Tx(t) it is actual transmission current waveform, AR (l) expression signals l auto-correlation.
The autocorrelogram picture of usual m-sequence pseudorandomcode is as shown in Figure 3.
Step 6：The response signal observed described in the response signal calculating observed according to record and the hair
Penetrate the cross-correlation function of machine actual transmission current waveform
Based on cross-correlation identification principle, to RxAnd T (t)x(t) cross-correlation calculation is done：
CR(Rx(t), Tx(t))=CR (g (t) * Iw(t)*hr(t), Tx(t))+CR (v, Tx(t)) (3)
Wherein CR (l, m) represents signal l and m cross-correlation.According to cross correlation property, because Tx(t) it is real signal, has：
CR(Rx(t), Tx(t))=Rx(t)*Tx(- t)=g (t) * Iw(t)*hr(t)*Tx(-t)+v*Tx(-t) (4)
Based on the h in step 4trAnd h (t)r(t) formula (4), can be rewritten as by relation：
CR(Rx(t), Tx(t))=g (t) * AR (Tx(t))+CR (v, Tx(t)) (7)
Wherein AR (l) represents signal l auto-correlation.
In above-mentioned steps, step 4 is performed before step 5 and step 6 certainly, and the execution of step 5 and step 6 can not
Successively, or even simultaneously perform.
Step 7：Based on cross-correlation identification principle, the complex effects of transmission signal autocorrelation sidelobe are eliminated, are realized to the earth
The high accuracy identification of impulse response
The discrimination method of the electromagnetic Earth impulse response of the present invention, eliminates transmission signal from phase in receiving and transmitting signal cross-correlation
The basic procedure for closing the complex effects of secondary lobe is as follows：
Following replace is carried out to formula (7)：
Then formula (7) can be rewritten as：
A (t)=g (t) * b (t)+cv (9)
A (t), g (t) and b (t) relation can be written as in discrete system in formula (9)：
Wherein, NgTo recognize the sampling number of the earth impulse response.Formula (10) matrixing is obtained：
A=BG+cv (11)
Wherein：
Wherein, n1And n2Respectively a (n) and maximum sampled point in b (n) sequences sequence number.
With formula (11) for model, by least square method, vector G is separated from vector A：
G=(BTB)-1BTA (12)
The G obtained in formula (12) is realized removes the influence of transmission signal autocorrelation sidelobe from transmitting-receiving cross-correlation, real
The high accuracy identification to the earth impulse response is showed.
, it is necessary to carry out debiasing processing to data, i.e., using LPF by signal bandwidth before the application above method
It is limited in corresponding scope；In identification process, successive ignition calculating can be carried out based on formula (12), be distinguished with further raising
Know precision.After identification is completed, G amplitude is modified according to receiver sample frequency, and G curves are smoothly located
Reason.
The high accuracy to electromagnetic Earth impulse response is realized using the discrimination method of the electromagnetic Earth impulse response of the present invention
After identification, its result can be applied not only to time-domain method, and frequency domain method is can also be used for after Fourier transform.
Below by specific test result, the invention will be further elaborated.
According to the requirement of electromagnetic Earth weighting function identification method of the present invention, ground using Chinese Academy of Sciences's electronics
The long earth lead source time domain electromagnetic prospecting system for studying carefully institute's independent research carries out method test.Use the m-sequence of the system
Fan-out capability is：The symbol width of m-sequence is that 12 grades of 1s to 1/8192s is adjustable, and the exponent number of m-sequence is 8 ranks to 18 ranks 11
Shelves it is adjustable, encode complete cycle number of repetition for 1 time to 9 times nine grades it is adjustable.For recording the earth observation signal and true transmitting electricity
The receiver for flowing waveform is SEP series of reception machines, and it passes through indoor standardization, it was demonstrated that it has height in corresponding frequency range
Uniformity.Receiver sample frequency 24kHz, dynamic range 120dB, observation voltage range ± 4.9V.
In actual observation, the pre-trigger sampling time is designed, duration 0.5s, design transmitting stops the post-sampling time, duration
2s.As shown in figure 4, the timing of whole observation process is as follows：Synchronous averaging is used to gather the earth observation signal and true hair first
Penetrate the receiver of current waveform, 100ns grades of synchronization accuracy, emitter starts to launch coding waveforms after 0.5s, wait emitter according to
After 1/8192s, 18 ranks, the transmitted waveform uninterruptedly circulated for 5 times setting are launched, emitter is stopped, but each receiver
Work on 2s, stops collection afterwards.
In the present embodiment, emission current is 17A, transmitting die opening 500m.Receiver is laid on firing cable axial direction, is received
Offset distance 1200m is sent out, electrically observation, electrode spacing 150m.M-sequence symbol width is 1/8192s, and m-sequence exponent number is 18 ranks, is followed
Ring number of times is 5 times.Fig. 7 is the details of actual transmission current waveform, and Fig. 8 is actual observation signal detail, and Fig. 9 is that receiving and transmitting signal is mutual
Result after correlation, corresponding with formula (3), Figure 10 is the not smoothed result after least squares identification, with formula (12)
Correspondence.Through with other geophysical method Comparative results, it was demonstrated that the accuracy of the above results.
In addition, the present invention has also carried out contrast test, can be to electromagnetic Earth pulse to prove the method according to the present invention
Response carries out the identification of higher precision.The method provided respectively using the art methods and the present invention of corresponding (16) is to reason
Recognized by the earth impulse response, as a result as shown in Figure 5.The Identification Errors of two kinds of discrimination methods, knot are evaluated according to formula (29)
Fruit is as shown in Figure 6.By Fig. 5 and Fig. 6 it will be clear that the discrimination method provided using the present invention can be lifted significantly
To the identification precision of the earth impulse response.
Wherein error represents Identification Errors, gaRepresentation theory calculates the earth impulse response, grRepresent that identification the earth impulse rings
Should.
Particular embodiments described above, has been carried out further in detail to the purpose of the present invention, technical scheme and beneficial effect
Describe in detail bright, it should be understood that the foregoing is only the present invention specific embodiment, be not intended to limit the invention, it is all
Within the spirit and principles in the present invention, any modification, equivalent substitution and improvements done etc. should be included in the protection of the present invention
Within the scope of.
Claims (2)
1. a kind of discrimination method of electromagnetic Earth impulse response, comprises the following steps：
Step 1, artificial source's electromagnetic method transmitted waveform is encoded according to Wiener-Hopf equations, the coding is using pseudo-
Random binary sequence, i.e. m-sequence；
Step 2, according to the coding generation transmitting drive signal；
Step 3, launched with the transmitting drive signal driving emitter；
Step 4, recorded using known to system response function relation between the tape deck or each device responded with identical systems
Device carries out record storage to the emitter actual transmission current waveform and the response signal observed simultaneously；Wherein described tool
Tape deck known to system response function relation meets following relation between having the tape deck or each device that identical systems are responded：
htr(t)=hr(t)：
Or htrAnd h (t)r(t) following relation is met：
htr(t)=f (t) * hr(t)；
Wherein, f (t) is known htrAnd h (t)r(t) relation function；htr(t) it is for recording Iw(t) receiver is
System response, hr(t) it is the system response of the receiver for response signal observation, Iw(t) it is the transmitting electricity of emitter reality output
Waveform is flowed, t is the time；
Step 5, the emitter actual transmission current waveform is calculated according to the emitter actual transmission current waveform of record
Auto-correlation function；The step of wherein calculating the auto-correlation function includes：
Calculate AR (Tx(t)), wherein Tx(t) it is actual transmission current waveform, AR (l) represents signal l auto-correlation,
Step 6, the response signal observed described in the response signal calculating observed according to record and the emitter
The cross-correlation function of actual transmission current waveform；The step of wherein calculating the cross-correlation function includes：
To RxAnd T (t)x(t) cross-correlation calculation is done：
CR(Rx(t), Tx(t))=CR (g (t) * Iw(t)*hr(t), Tx(t))+CR (v, Tx(t))；
Wherein, actual transmission current waveform is Tx(t) response signal, observed is RxAnd electromagnetic Earth impulse response is (t)
G (t), v are noise, and CR (l, m) represents signal l and m cross-correlation；
Step 7, based on cross-correlation identification principle, the complex effects of transmission signal autocorrelation sidelobe are eliminated by mathematical method, it is real
Now the high accuracy to the earth impulse response is recognized；The step is specifically included：
Definition
Then by CR (Rx(t), Tx(t))=Rx(t)*Tx(- t)=g (t) * Iw(t)*hr(t)*Tx(-t)+v*Tx(- t) matrix is turned to：
A=BG+cv；
Wherein：
NgTo recognize the sampling number of the earth impulse response；n1And n2Respectively a (n) and maximum sampled point in b (n) sequences
Sequence number；
Calculated by least square method, vector G is separated from vector A：
G=(BTB)-1BTA；
Thus obtained G is realized removes the influence of transmission signal autocorrelation sidelobe from transmitting-receiving cross-correlation, realizes to big
The high accuracy identification of ground impulse response.
2. the discrimination method of electromagnetic Earth impulse response according to claim 1, wherein also including between step 6,7 pair
Data carry out debiasing processing, i.e., the step of signal bandwidth being limited in corresponding scope using LPF；And
G amplitude is modified after identification is completed, in addition to according to receiver sample frequency, and G curves are put down
The step of sliding processing.
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| CN106059684B (en) * | 2016-07-14 | 2018-09-14 | 中国地质大学（北京） | A kind of noise processed system and method based on Correlation Identification |
| CN106125142B (en) * | 2016-07-14 | 2018-11-06 | 中国地质大学（北京） | A kind of Underground medium system and its method based on Correlation Identification frequency domain method |
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